Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/08—Fluid-actuated clutches with fluid-actuated member not rotating with a clutching member
  • F16D25/088—Fluid-actuated clutches with fluid-actuated member not rotating with a clutching member the line of action of the fluid-actuated members being distinctly separate from the axis of rotation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/08—Fluid-actuated clutches with fluid-actuated member not rotating with a clutching member
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/12—Details not specific to one of the before-mentioned types
  • F16D25/14—Fluid pressure control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/08—Fluid-actuated clutches with fluid-actuated member not rotating with a clutching member
  • F16D2025/081—Hydraulic devices that initiate movement of pistons in slave cylinders for actuating clutches, i.e. master cylinders
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
  • F16D2048/0215—Control by fluid pressure for damping of pulsations within the fluid system
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
  • F16D2048/0221—Valves for clutch control systems; Details thereof
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D2300/00—Special features for couplings or clutches
  • F16D2300/22—Vibration damping

Definitions

• the invention concerns a device for the prevention of the abuse of a dry-plate clutch for a motor vehicle with a manual gearbox, wherein the device acts jointly with a hydraulic master cylinder and a related slave cylinder in the operation of the clutch.
• a device of the above-mentioned type prevents the transfer of an excessive torque gradient (torque change per time unit) to the transmission due to a too rapid release of the clutch pedal during the engagement of the clutch.
• torque change per time unit torque change per time unit
• Such abuse of the clutch is especially risky when starting in first gear or in reverse gear, as well as when moving through the lowest gears when driving forwards.
• the sudden forces acting on the transmission during such a rapid engaging of the clutch often result in damage to the differential gears, the crown wheel and the pinion of the rear axle transmission unit, the drive shaft and the gearbox, but damage has also been found in engines due to frequent abuse of the clutch.
• Another known system for counteracting the abuse of the clutch works hydraulically via a choke device with a non ⁇ return valve installed in a bypass pipe.
• the non-return valve closes, thus causing all the hydraulic fluid to flow via the choke device, thereby providing a damping during the entire return movement of the clutch pedal.
• a damping takes place each time the clutch is engaged, irrespective of whether the clutch pedal is moved rapidly or slowly. Since the damping takes place during the entire return movement, a rapid gear change is virtually impossible, a fact which is particularly critical and awkward when changing gear at low temperatures since the damping increases and the clutch can slip.
• an electromagnetically controlled valve is incorporated which engages the device only when the clutch is used in connection with first gear and reverse gear. Thus there is no protection against abuse of the clutch in the other gears.
• the object of the invention is to provide a device of the type described in the introduction which is not encumbered by the above-mentioned disadvantages.
• Fig. 1 is a sketch of a hydraulic system for operating a clutch of a motor vehicle, wherein some of the components are shown in section, a clutch pedal is located in its rest position and a clutch of the dry-plate type is engaged.
• Fig. 2 is a longitudinal section through the device where it is located in its rest position.
• a system for operating a clutch 1 comprises a clutch pedal 2 which the driver of the vehicle can move with his foot, a hydraulic master cylinder 3 and a slave cylinder 4.
• the clutch pedal 2 is linked to the piston 5 of the master cylinder 3 via a piston rod 6 which projects from one end of the master cylinder's cylinder part 7.
• the master cylinder 3 communicates with the slave cylinder 4 by means of a conduit 8.
• the slave cylinder's piston 9 is linked via a piston rod 10 which projects from one end of the slave cylinder's cylinder part 11 to a rotatably mounted lever 12, whereby the clutch's thrust bearing 13 can be moved.
• the clutch plates can be moved in the known manner towards the right in fig. 1 to disengage the clutch and vice versa.
• valve unit 20 which constitutes an abuse device for the clutch 1, i.e. a device for counteracting the abuse of the clutch.
• This valve unit 20 comprises a preferably cylindrical valve housing 21 one end of which is connected to the master cylinder's cylinder part 7 via e.g. flange sections 23, 24 of the valve unit 20 or the master cylinder 3, the flange sections being capable of being connected to each other by means of screws 25 or the like, as indicated by chain-dotted lines.
• the valve unit 20 and the master cylinder 3 are preferably coaxial.
• the master cylinder 3 and the valve unit 20 communicate with each other via through-going passages 26 which are provided in a transverse end wall 27 at the right hand end of the valve housing 21.
• the conduit 8 whereby the slave cylinder 4 and the valve unit 20 communicate with each other is screwed into a threaded bore 28 at the other end of the valve housing 21.
• a seat 31 for a valve body 32 which is supported by an axially and centrally extending valve rod 33.
• This is slidably passed into a sleeve 34 which in turn is slidably passed into a central bore in the end wall 27.
• the valve rod 33 projects into a master cylinder and is closed with an end plate 35, a threaded end section of the valve rod 33 being screwed into a threaded hole in the end plate.
• the sleeve 34 comprises a first and a second sleeve section 36 and 37 which extend coaxially to each other and are permanently connected to each other by means of a threaded joint in order to permit the installation of the sleeve.
• the first sleeve section 36 has an end flange 38 and a stem section 39.
• the outer diameter of the end flange 38 and the second sleeve section 37 are larger than the diameter of the bore in the end wall 27, and the outer diameter of the stem section 39 is adapted to the diameter of the bore in the end wall 27, thus enabling the stem section 39 to be moved slidably to the right and the left in this bore, the sleeve's movement to the left thus being restricted by the second sleeve section 37 abutting against the right side of the end wall 27.
• the sleeve's inner diameter is adapted to the diameter of the valve rod 33, thus enabling it to be moved to the right and the left in relation to the sleeve 34, since such movement of the valve rod 33 can be restri ⁇ cted by the valve body 32 abutting against the end flange 38 of the first sleeve section 36 or by the end plate 35 abutting against the right end surface of the second sleeve section 37.
• a first helical spring 40 which is provided around the sleeve's 34 stem section 39 and between the end flange 38 and the end wall 27 attempts to move the sleeve to the left in relation to the valve housing 21.
• a second helical spring 41 which is provided around the valve rod 33 and extends between the end plate 35 and the second sleeve section 37 attempts to move the valve body 32 and the valve rod 33 to the right in relation to the sleeve 34.
• valve body 32 When the valve body 32 abuts against its seat 31, it divides the valve housing 21 into a first valve housing chamber 51 which faces the slave cylinder, and a second valve housing chamber 52 which faces the master cylinder.
• valve body 32 By means of at least one axially extending passage 53 through the valve body 32 communication is provided between these valve housing chambers 51, 52 even when the valve housing 32 abuts against its seat. Furthermore the valve body has a cylindrical piston section 54 whose outer diameter is only slightly smaller than the inner diameter of the first valve housing chamber 51. In the piston section 54 there is provided at least one axially extending, through-going, second passage 55. When the valve body is only affected by the springs 40, 41, an opening 56 is formed between the valve body 32 and the valve seat 31.
• the diameter of the valve body 32 is so much smaller than the inner diameter of the valve housing chamber 51 that the radially extending opening between these components does not cause any significant flow resistance for the fluid.
• the valve body does not abut against its seat,fluid will thus preferably flow through this radial opening rather than flowing through the first passage 53.
• the method of operation of the device is as follows.
• the piston 5 After some movement of the piston 5, it will abut against the end plate 35, whereupon the piston also moves the valve body 32 to the left via the valve rod 33. If the diameter of the first valve chamber 51 which constitutes a cylinder for the piston section 54 corresponds to the inner diameter of the master cylinder's cylinder part 7, no fluid will flow through the passage 55, since the amount of fluid flowing out of the first valve housing chamber 51 corresponds to the amount of fluid being forced into it from the master cylinder via the passage 26.
• the clutch will preferably be disengaged and brought into its maximum disengaged position without the end plate 35 having abutted against the right hand end of the second sleeve section 37.
• the clutch pedal 2 is first released, thereby moving the master cylinder's piston 5 to the right. Oil flows thereby from the slave cylinder 4 and into the master cylinder 3 via the valve unit 20. By means of the second spring 41 the end plate 35 will thereby be pressed against the master cylinder's piston 5 and force the valve body 32 to follow its movement. Since for the above-mentioned reason oil too preferably does not flow through the passage 55 in the valve body piston section 54 during this movement, the valve body 32 will not offer any significant resistance to the fluid flow.
• the second phase is concluded immediately after the clutch plates are engaged with full force.
• the transmission can be dimensioned correspondingly, i.e. it can be designed to be smaller, lighter and thus sub ⁇ stantially cheaper to produce.
• the object is achieved of dividing the engagement process into a first rapid phase and a second, slow phase, and of effecting a damping in the case of too rapid engagement.
• the rate of fluid flow to the right during the first phase of the engagement of the clutch will be greater in the first valve chamber 51 than in the master cylinder 3.
• the fluid will then attempt to move the valve body to the right but is prevented from doing so by the end plate 35 which abuts against the piston 5.
• Some of the fluid which is displaced by the slave cylinder therefore has to flow through the passage 55, but can be so extensively choked here that the movement of the piston 5 becomes slow. If the fluid is cold this effect is reinforced because the choking is added to the flow resistance in the conduit 8.
• valve body can be adapted to cooperation with the piston 5 of the master cylinder.
• the valve body can be adapted to cooperation with the slave cylinder's piston. Movement of this piston too is slow if the diameter of the piston section 54 is significantly smaller than the diameter of the piston.
• the diameter of the valve body's valve 54 is advantageous for the diameter of the valve body's valve 54 to be equal to or only slightly smaller than the diameter of the piston 5 or 9 with which the valve body is connected.
• the characteristics of the first spring 40 can, for example, be adapted to the characteristics of the spring device which is included in the clutch 1 and which attempts to engage it in such a way that the valve body 32 is moved away from its seat 31 by the spring 40 after the clutch 1 has been engaged. If the force exercised by the clutch's spring in relation to the force exercised by the first spring is thereby reduced during the third phase in relation to the second phase, the differential pressure exercised on the closed valve body would be able to be so small that the valve unit opens once again and the first passage no longer chokes the oil flow.
• valve body 32 and the valve rod 33 in relation to the sleeve 34 can instead be restricted by the end plate's 35 abutment against the second sleeve section 37, which in turn restricts the clutch pedal's and the clutch's movement, this restriction possibility will not normally be used, since the movement of the pedal and the clutch will preferably be restricted in another way, e.g. by means of a stopper which is attached to the body against which the pedal abuts.
• valve body's piston section 54 can be omitted- The valve body will then be moved to the closed position due to the differential pressure over this as a result of the drop in pressure which is caused by the fluid flowing through the opening 56.
• this is less advantageous because the shape of this opening will be decisive for the extent of the pressure difference, which will, e.g., require an extremely accurate setting of the axial distance between the valve body and the valve seat during the installation of the valve unit.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19894702

Family Applications (1)

Country Status (8)

Cited By (3)

Families Citing this family (7)

Citations (6)

Family Cites Families (8)

• 1991
  • 1991-12-20 NO NO915047A patent/NO175654C/no unknown
• 1992
  • 1992-12-18 JP JP51157293A patent/JP3283879B2/ja not_active Expired - Fee Related
  • 1992-12-18 WO PCT/NO1992/000202 patent/WO1993013328A1/en active IP Right Grant
  • 1992-12-18 DE DE69204685T patent/DE69204685T2/de not_active Expired - Fee Related
  • 1992-12-18 BR BR9206968A patent/BR9206968A/pt not_active Application Discontinuation
  • 1992-12-18 EP EP93901482A patent/EP0617767B1/en not_active Expired - Lifetime
  • 1992-12-18 US US08/244,723 patent/US5479779A/en not_active Expired - Fee Related
  • 1992-12-18 KR KR1019940702147A patent/KR940703976A/ko not_active IP Right Cessation

Patent Citations (6)

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